Creeping, crawling caterpillars

How these roly-poly, spineless worms are serving as role models for soft material robots.

Sometimes it pays to be spineless. Take the caterpillar — it can squirm and crawl in ways that would make a contortionist green with envy.

One such animal, a green tobacco hornworm, dangles off Barry Trimmer's finger, half of its body squirming and bending in mid-air. What fascinates Trimmer, a Tufts University biology professor, is how caterpillars can move in ways animals with spines and skeletons can't.

"This little guy can grip and hold and move, and we're trying to make devices that are going to be able to do this," says Trimmer.

By devices, Trimmer is referring to a robotic caterpillar. Already, he and his team have molded plastic models to simulate the caterpillars' movements. With support from the National Science Foundation (NSF) and the Defense Advanced Research Projects Agency (DARPA), these caterpillars could very well be the nucleus of a whole new field of robotics.

Imagine small, squishy robots that could be dropped into tall trees to survey the canopy of a forest or be flown into space to monitor equipment on board the International Space Station.

"It can burrow, it can climb, and it can navigate through complex terrain," notes Trimmer. "What we hope to do is make an extreme form of robot that is able to perform all of those tasks wherever it finds itself."

Caterpillars don't have big brains and these robots won't either. "Instead what you have is a body that can perform most of the tasks itself," explains Trimmer. "What we're trying to do is understand how the nervous system and the body work together to create those complex movements. And if you think about it, that could be really interesting because if you don't have a rigid skeleton, if you don't have bones, you can move in ways that stiff animals can't."

To make a robot patterned on caterpillars, Trimmer and his team study every aspect of them, down to the DNA.

"I've been working with these animals for 20 years. I still can't believe the transformation from caterpillar to the moth. It's all in one genome. It's a bit like reprogramming a battleship, using the same blueprint you started with, and building a 737 jet."

Trimmer hopes in the next five to 10 years, small, squishy robots will be a reality. Some, he says, might even be safe enough to swallow in order to diagnose disease or deliver medications.